The documented association of Streptococcus bovis fecal carriage and carcinoma of the colon and of S. bovis sepsis and occult colonic neoplasms prompt intensive investigation into these associations. The epidemiology of S. bovis will be further studied by obtaining fecal cultures from normal controls over time, from subjects on both standard and vegetarian diets, from patients with non-colonic gastrointestinal neoplasma, from patients with inflammatory bowel disease and from those with benign colonic polyps. Patients with S. bovis septicemia will undergo extensive gastrointestinal evaluations. Search will be undertaken for any particular biotypes of S. bovis carried by patients with colon cancer and for any serologic response by normals or colon cancer patients to the S. bovis carrier state.